In recent years, phased array systems, which steer the direction of antenna beams of high frequency, such as the millimeter wave band, are used in fields of communications, sensors, and the like. Phased array systems employ phase shifters, for example. Phase shifters are desirably configured to shift the phase from 0 to 360 degrees while keeping the amplitude of the signal fixed.
Some related techniques are disclosed by Japanese Laid-open Patent Publication Nos. 2001-168668, 2002-246802, and 5-37318.